DENOX abatement plants through special catalytic beds and urea injection.

Airprotech is supplying DeNOx plants for many years in different industrial sectors.

This kind of application is recently requested in co-generation field, in particular downstream of internal combustion motors powered by biodiesel or by vegetable oils. Such combustibles give high advantages compared to diesel but, at the same time, produce bigger quantity of NOx and accordingly require an appropriate abatement system in order to respect the emission limits required by law.

The most effective process to eliminate nitrogen oxides (NOx) is the one based on the selective catalytic reduction (SCR), technology that takes advantage of the tendency of ammonia (contained in urea) to react with nitrogen oxides in presence of selective catalyst that allows a high performance.

One of the reactions is:

The polluted air to be treated, coming from the motors, is sucked up from a centrifugal fan located downstream of the plant, passes first the blending unit where the urea is dosed through an air atomization nozzle and then introduced on the catalysis bed where it meets with the catalyst on which the reduction reaction occurs and turns the nitrogen oxides into N2.
Once happened the reaction, the cleaned air that comes out from the catalysis unit is sent to the atmosphere through a suitable chimney.
The catalyst chosen for the reduction is honeycomb type that has titanium as active catalytic component. This kind of catalyst is poisoning proof and can bear high temperature.

If the temperature of the fumes to be treated is particularly high, it is foreseen the possibility to reduce it by blending it with ambient air through a modulating valve. This loop will work in control of the temperature and in a completely automatic way.